The present invention relates to a self-pumping thrust bearing for electric machines having a vertical shaft, particularly hydroelectric generators.
A self-pumping thrust bearing is disclosed in German Patent No. 901,360 in which overlapping stationary and rotating cylinder walls are arranged facing each other on the radially inner side of the thrust bearing cup and seal the latter against the shaft, and are intended to prevent air from penetrating the oil and thus prevent the oil from foaming.
Air bubbles entering the oil being circulated in a thrust bearing of the type described in German Patent No. 901,360 can lead to a large drop in oil pressure, which pressure is required to circulate the oil, and therefore to an impairment of the cooling of the bearing. In addition, a film of foamed oil has a reduced load-carrying capacity. Even when several cylinder walls are arranged overlapping with a rotating wall, it is still possible that air bubbles can enter into the oil space of the thrust bearing cup.